package gitobject;

import java.io.*;


import fileoperation.FileReader;
import sha1.SHA1;
import repository.Repository;
import zlib.ZLibUtils;

public class Commit extends GitObject{
    protected String tree; 		// the sha1 value of present committed tree
    protected String parent; 	// the sha1 value of the parent commit
    protected String author; 	// the author's name and timestamp
    protected String committer; // the committer's info
    protected String message; 	// the commit memo

    public String getParent(){return parent;}
    public String getKey(){return key;}
    public String getTree(){return tree;}
    public String getAuthor(){return author;}
    public String getCommitter(){return committer;}
    public String getMessage(){return message;}

    public Commit(){}
    /**
     * Construct a commit directly from a file.
     * @param
     * author, committer, message参数在git commit命令里创建
     * @throws Exception
     */
    public Commit(String treePath, String author, String committer, String message) throws Exception {
        this.fmt = "commit"; 	//type of object
        this.tree = new Tree(new File(treePath)).getKey();
        this.parent = getLastCommit() == null ? "" : getLastCommit(); //null means there is no parent commit.
        this.author = author;
        this.committer = committer;
        this.message = message;

        /*Content of this commit, like this:
         *tree bd31831c26409eac7a79609592919e9dcd1a76f2
         *parent d62cf8ef977082319d8d8a0cf5150dfa1573c2b7
         *author xxx  1502331401 +0800
         *committer xxx  1502331401 +0800
         *修复增量bug
         * */
        this.value = "tree " + this.tree + "\nparent " + this.parent+ "\nauthor " + this.author + "\ncommitter " + this.committer + "\n" + this.message;

        key = genKey();
        compressWrite();

    }

    /**
     * Construct a commit from a built tree.
     * @param
     * author, committer, message参数在git commit命令里创建
     * @throws Exception
     */
    public Commit(Tree t, String author, String committer, String message) throws Exception {
        this.fmt = "commit"; 	//type of object
        this.tree = t.getKey();
        this.parent = getLastCommit() == null ? "" : getLastCommit(); //null means there is no parent commit.
        this.author = author;
        this.committer = committer;
        this.message = message;

        /*Content of this commit, like this:
         *tree bd31831c26409eac7a79609592919e9dcd1a76f2
         *parent d62cf8ef977082319d8d8a0cf5150dfa1573c2b7
         *author xxx  1502331401 +0800
         *committer xxx  1502331401 +0800
         *修复增量bug
         * */
        this.value = "tree " + this.tree + "\nparent " + this.parent + "\nauthor " + this.author + "\ncommitter " + this.committer + "\n" + this.message;
        key = genKey();
        compressWrite();
    }

    /**
     * Deserialize the commit object from its key(commitId)
     * @param commitId
     */
    public static Commit deserialize(String commitId) throws Exception{
        try{
            File file = new File(path + File.separator + commitId);
            Commit commit = new Commit();
            FileInputStream is = new FileInputStream(file);
            byte[] output = ZLibUtils.decompress(is);//反序列化并解压缩
            is.close();
            String content = new String(output);//将字节数组转化为字符串
            commit.value = content;

            commit.key = commitId;
            commit.fmt = "commit";
            commit.tree = FileReader.readCommitTree(content);

            commit.parent = FileReader.readCommitParent(content);
            commit.author = FileReader.readCommitAuthor(content);
            commit.committer = FileReader.readCommitter(content);
            commit.message = FileReader.readCommitMsg(content);

            return commit;
        } catch(Exception e){
            e.printStackTrace();
        }
        return new Commit();
    }
    /**
     * Generate the hash value of this commit.
     * @return key
     * */
    public String genKey() throws Exception {
        key = SHA1.getHash(value);
        return key;
    }




    /**
     * Get the parent commit from the HEAD file.
     * @return
     * @throws IOException
     */
    public static String getLastCommit() throws IOException {
        File HEAD = new File(Repository.getGitDir() + File.separator + "HEAD");

        String path = getValue(HEAD).substring(5).replace("\n", "");
        File branchFile = new File(Repository.getGitDir() + File.separator + path);

        if (branchFile.isFile()) {
            return getValue(branchFile);
        } else {
            return null;
        }
    }
}
